Otus kennicottii
western screech owl

Western screech-owls (Otus kennicotti) inhabit western North America, northwestern Mexico and coastal regions of the Pacific Northwest (Cannings and Angell, 2001). Ranging as far north as southeast Alaska and southern Canada to the Baja penninsula and into Mexico, western screech-owls make their homes within the diverse communities of the riparian deciduous woodlands of North America (Cornell Lab of Ornithology, 1999). Within the last 40 years, the range of western screech-owls has expanded as far east as Texas (perhaps due to increased tree-planting) and as a result they are now found sympatrically with their very close relative, eastern screech-owls (Otus asio). ()

Western screech-owls usually inhabit low elevation riparian and deciduous oak woodland commmunities (Campbell et al., 1990; Cannings, 1997; Cannings and Angell, 2001). They will often inhabit streamside groves, deserts, suburban parks and gardens (Cornell Lab of Ornithology, 1999). The abundance of O. kennicotti is positively associated with overstory cover of mesquite (prosopis) and understory cover of native perennial vegetation (Hardy et al., 1999).

Within the United States O. kennicottii occurs in high densities in the following regions:

Arizona: mesquite-riparian zones of the Sonoran Desert. In particular, western screech-owls are strongly associated with structurally diverse uplands of the Sonoran Desert, containing saguaros (Carnegiea gigantea), mesquite woodlands and cottonwood (Populus)-willow (Salix) riparian areas (Hardy et al., 1999).

Texas: lower elevations in riparian zones dominated by Arizona sycamore (Plantanus wrightii) as well as pure oak habitats (Gelbach and Leverett, 1995; Cannings and Angell, 2001).

California: western screech-owls are strongly associated with areas with fan palms (Washingtonia filifera) and oak woodlands (Feusier, 1989; Noble, 1990; Lehman, 1994; Cannings and Angell, 2001).

Washington and Alaska: western screech-owls are found in riparian habitats and the mixed forests of coastal regions consisting of big-leaf maple (Acer macrophyllum), red alder (Alnus rubra), Douglas fir (Psudotsuga menziesii), western hemlock (Tsuga heterophylla)and western red cedar (Thyja plicata) (Kitchin, 1949; Cannings and Angell, 2001).

Colorado: western screech-owls are primarily found in rural developed areas and areas with broad-leaved cottonwoods along river basins. They are also associated with farmyards containing mature, unpruned cottonwood trees and shrubbery. Throughout their range they are found in urban and suburban parks as well as residential areas (Levad, 1998; Cannings and Angell, 2001). ()

Otus kennicottii is a small owl with feathered "ear tufts". Adults are 19 to 25.5 cm in length; and weigh 170.1 g on average. Male wingspans are 168.4 mm, female wingspans are 174.5 mm. Sexes are alike in plumage characteristics. Plumage of western screech-owls is generally monomorphhic in a given area; brown or gray-brown in the northwest and gray in southern deserts. Some populations in the coastal regions of the Pacific Northwest are more variable in color, often displaying reddish-brown morphs (Cannings and Angell, 2001).

The face of western screech-owls is pale with a dark lateral border, their underparts are streaked and barred. They have yellow eyes and dark bills. Their feet and toes are feathered in northern populations but bristled in southern deserts (Cannings and Angell, 2001). ()

Western screech-owls usually live from 1 to 8 years in the wild. The longest recorded lifespan for a western screech-owl in the wild is 13 years, in captivity the longest recorded lifespan is 19 years.

The wings of Otus kennicottii have a low aspect ratio, which is typical of sit-and-wait predators that do not fly long distances (Johnson, 1997; Cannings and Angell, 2001). Young are very capable climbers and adults are able to effectively walk into thickets for roosting (Cannings and Angell, 2001).

Otus kennicottii has been observed to bathe occasionally. Males roost in close proximity to the nest during breeding season, this reduces the flying distance to the nest throughout the nestling period. Males are joined by the females during the last weeks of the nestling period and they systematically position their roosts opposite the nest cavity entrance to provide increased protection from crows, jays, and other diurnal predators (Cannings and Angell; 2001).

Territories are defended year-round, however, responses to calls by conspecifics decline during the incubation and nestling periods. Western screech-owls react agressively to calls of spotted owls (Strix occidentalis) and great horned owls (Bubo virginianus) (Cannings and Angell; 2001).

Throughout the year, western screech-owls live in pairs. However, they can be found in small family groups before the juvenilles disperse (Cannings and Angell; 2001). ()

Home Range

We do not have in formation on home range for this species at this time.

The song of Otus kennicottii consists of 5 to 15 hollow whistle hoots of a single pitch that accelerate towards the end in a "bouncing ball" sequence (Cannings and Angell, 2001). ()

Western screech-owls are "sit-and-wait" predators. They leave their roosts to forage just before sunset. Their hunting technique may predispose the northern populations to primarily hunt mice. When foraging near bodies of water, O. kennicottii will perch and wait until crayfish emerge in the shallows, then it will fly down and grab one by dipping only its legs into the water. It will also hawk for flying insects and glean arthropods from folage, but it prefers to catch small, terrestrial mammals (Hayward and Garton, 1988; Cannings and Angell, 2001).

Songbirds are a frequent meal for O. kennicottii and as a result the owls are often mobbed in response to their threats. Frequent mobbers are those songbirds that are most often preyed upon (for example, northern cardinals and white-throated sparrows). Mobbing by songbirds occurs most frequently during the spring and early summer nesting period. Most mobbers are permanent residents that are always part of the avian prey community. Birds use seasonal song, age-realted plumage and nest-area cues of western screech-owls to help assess the danger of predation (Gehlbach and Leverett, 1995).

Western screech-owls commonly eat: small mammals, birds, annelid worms, insects, crayfish and fish. ()

Western screech-owls typically react to the presence of predators with bill snaps and bark calls.

Known predators include: spotted owls (Strix occidentalis), great horned owls (Bubo virginianus), barred owls (Strix varia), raccoons (Procyon lotor), gopher snakes (Pituophis melanoleucus) and crows and jays (family Corvidae). ()

Colonies of tree ants (genus Crematogaster) will often occupy the nest sites of Otus kennicottii and apparantly protect the nest from disturbance by biting or stinging potential predators. This relationship seems to be a unique symbiosis in the genus Otus, however, it is infrequent (McCallum et al., 1995).

The abundance of western screech-owls is positively associated with the abundance of elf owls (Micrathene whitneyi) in the Sonoran Desert (Hardy et al., 1999). ()

There are no known adverse affects of western screech-owls on humans.

Western screech-owls can live in suburban habitats where nest and root sites are available. Pairs nesting in these suburban habitats are often tolerant of humans close to their nests , this allows birders to visit their nest sites (Cannings and Angell, 2001). In addition, Otus kennicottii (previously thought to be conspecific with Otus asio), challenges researchers to discover more about this magnificent bird and hopefully urge conservationists to adopt an active role in habitat preservation. ()

Western screech-owls are closely linked to the riparian habitats of its range; these areas are often the first habitat in any given area to suffer the effects of urban development. Although pairs nesting in suburban areas are generally tolerant of humans close to their nests, they may be sensitive to local disturbance at nest sites from frequent visits by birders (Hardy et al., 1999; Cannings and Angell, 2001). Breeding populations are continually threatend by rapid urbanization and degradation of habitat, and face possible competition from exotic species such as European starlings (Sturnus vulgaris) (Hardy et al., 1999).

Currently there are no official data on the trends of population densities for western screech-owls. However, their populations are probably declining slowly as habitat is lost (Cannings and Angell, 2001).

Western screech-owls are protected by the US MBTA and are listed under Appendix II by CITES, but are not listed on the US Federal List or the IUCN Red List. ()

Western screech-owls (Otus kennicottii), long considered conspecific with eastern screech-owls (Otus asio), were finally recognized as a seperate species in 1983. Their re-classification was based on signifigant differences in vocalization and behavior between the two species (Cannings and Angell, 2001).

Despite its abundance, little is known about Otus kennicottii, including basic parameters such as survival rates and breeding success. Priorities for future research include vocalization studies that could focus on the geographic variation in calls, and genetic analysis of various subspecies for taxonomic purposes (Cannings and Angell, 2001). ()